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Syslog message: XMCHIP.*FI.*Aliasing on allocates error.*Pipe count



Article ID: KB31686 KB Last Updated: 06 Oct 2021Version: 4.0

The "Aliasing on allocates error" message reports a transient hardware issue. This article provides the reason for the error and details the steps to perform to troubleshoot the error.

This is a Troubleshooting Article for a PFE ASIC Syslog Event.
To view other documented syslog events related to XMCHIP, XLCHIP, MQCHIP, LUCHIP, EACHIP, and PECHIP, see KB31893 - Index of Articles for Troubleshooting PFE ASIC Syslog Events.




When an "Aliasing on allocates error" event occurs, a message similar to the following is reported along with “Cell underflow” or “Reorder cell timeout” errors:

<Host> <FPC#> XMCHIP(x): FI: Aliasing on allocates error - Pipe count 0, Count 1
<Host> <FPC#> XMCHIP(x): FI: Cell underflow at the state stage - Stream 148, Count 231
<Host> <FPC#> XMCHIP(x): FI: Cell underflow at the state stage - Stream 101, Count 201


<Host> <FPC#> XMCHIP(x): FI: Aliasing on allocates error - Pipe count 0, Count 1
<Host> <FPC#> XMCHIP(x): FI: Reorder cell timeout - Stream 45, Count 35 
<Host> <FPC#> XMCHIP(x): FI: Reorder cell timeout - Stream 25, Count 35 


  • Service Impact: Counter reports the number of packets dropped due to failing packet CRC check.
  • There is no permanent impact on packet forwarding.



“Aliasing on allocates” errors can be seen with “Cell underflow” or “Reorder cell timeout” errors. These are transient hardware errors. By comparing the stream numbers in each log, we can determine which is the faulty FPC. If the stream numbers are different, then the reporting PFE is usually the culprit. If the event is reported from several PFEs with the same stream number, the sending PFE is the culprit. 



Perform these steps to determine the cause and resolve the problem (if any). Continue through each step until the problem is resolved.

  1. Collect the show command output.

    Capture the output to a file (in case you have to open a technical support case). To do this, configure each SSH client/terminal emulator to log your session.

    show log messages
    show log chassisd
    start shell network pfe <fpc#>
    show nvram
    show syslog messages

  2. Analyze the show command output.

    In the show log messages output, review the events that occurred at or just before the appearance of the "Aliasing on allocates error" message. Frequently, these events help identify the cause.

  • Determine the FPC originating the bad packets.

  • If multiple syslogs from the same FPC are listing different stream numbers, then the FPC originating the logs is the potentially faulty FPC.

  • If multiple syslogs from many FPCs or PFEs are listing the same stream number, then map the stream number to the originating FPC.

  • Reset the FPC determined in the step above.

  • If the logs recur after reset, contact your technical support representative immediately.

This article is indexed in KB31893 - primary Index of Articles for Troubleshooting PFE ASIC Syslog Events; tag XMCHIPTSG

Tip: When looking at an event in the logs, it is important to focus on the first error message in a collection of syslog messages. The first error message is usually the cause of all the follow-on error messages. The follow-on collateral damage error messages can be ignored.


Modification History:

2020-03-05: Article links updated; article reviewed for accuracy

2019-10-14: Article reviewed for accuracy; no changes required.


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